The present invention, in some embodiments thereof, relates to matrices which comprise oxygen carriers and methods of generating and using same for tissue formation, regeneration and/or repair.
Mesenchymal stem cells (MSCs) are multipotential stem cells, which can differentiate into the osteogenic, adipogenic, chondrogenic and tenogenic lineages. These cells can be isolated from bone marrow, adipose tissue, muscle tissue, umbilical cord blood and peripheral blood. Genetically engineered—MSCs, which over express osteogenic genes, such as bone morphogenetic proteins (BMP) can promote differentiation of cells into the osteogenic lineage in an autocrine or paracrine manner. BMPs are members of the transforming growth factor beta (TGFβ) superfamily and are known for their ability to induce bone formation in ectopic and orthotropic sites. Recent studies have shown that BMP-2, -6, -7 and -9 are potent inducers of osteogenic differentiation.
In vitro studies, which tested the effect of low oxygen levels on MSCs from various tissue sources, showed that while adipose-derived MSCs grown in culture dish under low oxygen level demonstrate inhibition of osteogenic differentiation (Malladi, Xu et al. 2006), bone marrow-derived MSCs cultured under hypoxic conditions show higher levels of osteoblastic and adipocyte markers (Grayson, Zhao et al. 2006). In addition, bone marrow-derived MSCs, which were subjected to short exposures of hypoxic conditions, exhibit no alterations in the level of osteogenic differentiation as determined by transcriptional profiles (Martin-Rendon, Hale et al. 2006). Yet, multipotential human stromal cells isolated from vertebrae bone marrow exhibit decreased osteogenic differentiation under low oxygen tension of 3% (D'Ippolito, Diabira et al. 2006).
One of the major hurdles in bone tissue engineering is the lack of oxygen supply to the forming tissue resulting in cell death and probably loss or delay of the osteogenic potential. Hyperbaric oxygenation therapy that elevates oxygen levels in tissues was found to increase osteoblastic activity and to accelerate bone formation induced by recombinant human BMP-2 protein (Muhonen, A., et al., 2004, Int. J. Oral Maxillofac Surg 33, 173-178).
Attempts to induce blood vessels formation in the forming bone tissue, mainly by using vascular endothelial growth factor (VEGF) have been reported (Huang, YC., et al., 2005, J. Bone Miner. Res. 20: 848-857; Klopper, J., et al., 2008, Microvasc. Res. 75: 83-90).
Khattak et al. (Biotechnology and Bioengineering, 96: 156-166, 2007) describe the use of alginate gels containing perfluorocarbons such as perfluorotributylamine (PFTBA) and perfluorooctylbromide (PFOB) for increasing oxygen availability and HepG2 cell viability.
WO 01/76507 describes the use of a serum-free aqueous medium comprising an oxygen carrier such as perfluorocarbons for transplantation of stem cells into vertebrate central nervous system for the treatment of neurodegenerative diseases.
Radisic et al. [Nat Protoc 3, 719, 2008; Tissue Eng 12, 2077, 2006; Am J Physiol Heart Circ Physiol 288, H1278, 2005] found that perfluorocarbons—supplemented medium enhances oxygen transport and cell viability of cardiomyocytes and fibroblasts cultured on a highly porous elastomer with a parallel array of channels.
Fraker et al. 2007 (Stem cells 25: 3155-3164) describes the use of the two-dimensional perfluorocarbon-silicone membrane for culturing of pancreatic buds.
Additional background art includes Chin K, et al., 2008 [Biotechnol. Prog. 24(2):358-66. Epub 2008 Feb. 23].